I would like to bitstream DTS-HD with foobar2000 through HDMII have installed the WASAPI plugin but if I want to play a .dts or .dtshd file I get an unsupported file format errorThen if I install dts plugin as well foobar decodes dts and sends multichannel way through HDMI...

I was under the impression that bitstreaming means bypassing all post-processing (mixer), but that could include a pre-processed signal like decoded dts (=LPCM), while pass-through refers to sending the raw undecoded signal to another device. But maybe it's the same thing?